textproduct: Quad Cities

KEY MESSAGES

- Another cluster of showers and storms is likely to impact portions of the area late this evening through the overnight period, which could initially bring a risk for localized damaging winds. Of more concern will be the potential for additional episodes of flash flooding (some potentially significant) for areas that have been hardest hit over the past few days receiving 4" to 6" of rain so far.

- Active weather pattern to continue through the weekend, with greatest storm coverage at night into the morning. Due to successive rainfall events, additional totals of 2 to 4 inches by Saturday morning are favored with localized higher values likely(70%), continuing the flash flood threat.

SHORT TERM /THROUGH SATURDAY/

Issued at 334 PM CDT Fri Aug 14 2026

After a lull in the thunderstorm activity from late this morning into early this evening, another wave or remnant MCV currently over west-central Iowa is expected to reach the western outlook area by early tonight. CAMs have consistently showed a regeneration of deep convection along the leading flank of the MCV somewhere in the 5 PM to 9 PM timeframe across parts of central/south-central Iowa, then growing upscale into an organized MCS as it rolls eastward into eastern Iowa and eventually west-central Illinois. Exact north-south placement is in question; however, the most favored zone is south of Highway 30 and along/north of Highway 34. This places the tier of counties just south of I-80 that got hit the hardest with heavy rainfall and flash flooding last night/early this morning potentially in the swath of heaviest rainfall again tonight. A very moist atmosphere with near ~2" PWATs, high freezing levels promoting efficient warm-rain processes, and relatively slow storm motions are all supportive of a notable flash flood risk through the overnight period with peak hourly rain rates between 1-2" possible. WPC has maintained the Moderate Risk for flash flooding (level 3 of 4) for most of the area except the far north which is in a Slight Risk (level 2 of 4).

As for total rainfall amounts, the latest HREF mean has a west-east axis of 1-3"+ along the I-80 and Highway 34 corridors. The LPMM HREF has isolated pockets of 4-5"+ south of I-80, which is an indication of the higher end amounts that could occur on an isolated basis. The Flood Watch remains in effect into Saturday morning with the overnight heavy rainfall likely to exacerbate flooding impacts in poor drainage areas and along creeks, streams, and tributary rivers.

There is also a Slight Risk (level 2 of 5) for severe storms along and south of Highway 30 late this evening into tonight with localized damaging winds as the primary threat with any bowing segments that develop. A few brief QLCS/spin-up tornadoes are also possible with any balanced bowing segments -- SPC has highlighted a portion of southeast Iowa with slightly higher tornado probabilities compared to areas to north and east (5% chance within 25 miles of a point). Scattered showers and storms will likely linger into the mid morning hours on Saturday before gradually decreasing in coverage and shifting off to the east.

LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/

Issued at 334 PM CDT Fri Aug 14 2026

An active period with brief moments of respite will continue this week.

Saturday Afternoon and Evening... Saturday afternoon and evening will be one such brief moment of respite from the constant onslaught of rain this week. The primary concern would be the need for any heat headlines as heat and humidity remain in place. The primary area to watch would be along and south of the HWY 34 corridor, where HREF probabilities of greater than 95 degree heat indices are 50-90% from north to south. The NBM, which has had a running warm bias, brings these probabilities (50-90%) further north to along the HWY 30 corridor. As such, depending on the evolution of storms through Saturday morning, a heat headline may be needed.

Saturday night through Tuesday... Another wave moves through late Saturday night through Sunday morning, bringing yet another round of rain to the area. Severe risk is unlikely due to low bulk shear, but there will be enough instability to support embedded thunderstorms. Rainfall totals will be on the lower side, as seen by NBM probabilities of 30-50% of exceeding 0.10 inches. CAMs do hint that locally higher amounts will be possible wherever embedded thunderstorms occur. Behind these showers, a cold front will bring cooler temperatures to the region. These will last through midweek as we remain under the influence of surface high pressure.

Wednesday through Friday... By midweek, midlevel flow will transition from zonal to northwesterly flow. This will help sustain the cooler temperatures established earlier in the week. Additionally, signals are in place for waves to move through the flow, bringing chances for more active weather.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1248 PM CDT Fri Aug 14 2026

Poor aviation conditions expected into Saturday AM with periods of MVFR/IFR ceilings/visibilities and bouts of showers and thunderstorms. The most widespread rain and highest chances for storms will be overnight into early Saturday AM (roughly 03Z to 12Z/Saturday). Any storms will be capable of producing very heavy rainfall and brief visibility reductions to LIFR. The low ceilings are then expected to last through the mid/late morning on Saturday before improvement to VFR.

HYDROLOGY

Issued at 1122 AM CDT Fri Aug 14 2026

Rainfall ranging from 3 to 6 inches, with locally higher amounts occurred last night across parts of the area. The area was generally two counties wide, running from Keokuk County Iowa into southern Henry County Illinois in the north, and Highway 34 in the south.

More heavy rainfall, potentially another 3 to 6 inches with locally higher amounts, is expected tonight into Saturday morning. Some models are indicating the same areas that were hit last night would get hit again. Other models are slightly further south.

Regardless of the location, soils across the area run from moist to saturated. Heavy rainfall tonight has a high probability of resulting in more flash flooding that may be considerable.

The persistent rounds of rain are causing a slow rise on area rivers.

Based on rainfall through tonight, most rivers are projected to only see within bank rises. However, slight changes in the amount each basin receives over the next two days may cause some rivers to go into flood, especially tributary rivers.

A better way to look at this is to look at the probabilities of reaching minor and moderate flood stages using an ensemble spread of precipitation over the next 10 days.

For the following rivers there is a 30-50 percent probability of achieving minor flood stage through August 24th;

English and Iowa Rivers. Cedar River south of I-80

These rivers also have a 20-30 percent probability of achieving moderate flood stage.

For the Skunk River, the probability of achieving minor flood stage is 30 percent, and 20 percent for moderate flood stage.

For the Wapsipinicon River, the probabilities vary considerably. Anamosa has a 37 percent change of reaching minor flood stage while near DeWitt the probability is 83 percent.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Flood Watch through Saturday morning for IAZ040>042-051>054- 063>068-076>078-087>089-098-099. IL...Flood Watch through Saturday morning for ILZ007-009-015>018- 024>026-034-035. MO...Flood Watch through Saturday morning for MOZ009-010.